The Not-So-Computational Brain and Fantasy Cosmology

An essay entitled “The Empty Brain” has been bouncing around the internet over the past week, claiming that “Your brain does not process information, retrieve knowledge or store memories. In short: your brain is not a computer.”

Now, rumor has it some of you may not hang out around neuroscientists all day? In that case, let me fill your internet with an expert reaction.

This essay overstates many points, and presents many issues in imprecise or misleading ways. But, fundamentally, it is correct.

Let’s look at some of Dr. Epstein’s key points:

• We don’t have representations

It depends how abstract you want to get. Certainly, something in your brain reflects each skill and prediction and bit of information you have. I call this a “neural representation,” but that’s a technical term, not a literal claim. This “representation” isn’t a discrete thing, an arrangement of data; it’s some fluid time-share assemblage of synaptic weights and connections and more. Our “neural representations” are nothing like computer representations.

Later in the piece, Epstein uses the example of baseball outfielders to explain action without internal models. However, a pure organism-world interaction doesn’t explain human behavior: we correct our movements before we receive sensory feedback! We need internal models of body and world characteristics (e.g. how your joints will interact when you perform a complex movement), but that doesn’t require information processing.

Use one neural network to model another? That sounds hard, doesn’t it? Well, that’s why the cerebellum has as many neurons as the rest of your brain combined.

• Brains don’t perform algorithms

Brains can perform algorithms – after all, you can perform an algorithm, and surely your brain made that happen. But this is a bad way to describe what brains are doing. No part of the brain is operating algorithmically; we have a big mess of automatic processes and linguistic consciousness scaffolded atop basic sensory-motor functions.

• Brains don’t store memories

A wild overstatement. But we certainly don’t store memories like computers, nor even like we introspectively think we do. We store certain key details and associations, and re-invent all the details when we recall it. Moreover, as with “representations,” this “storage” is distributed widely across the brain. Nothing like conscious memory gets stored in single neurons.

When Epstein says “no image of the dollar bill has in any sense been ‘stored’ in Jinny’s brain,” this is obviously false. Any sense is a low bar, and it has certainly been stored in some sense. But only a vague, metaphorical, un-computer-like sense.

• The uniqueness problem

“There is no reason to believe that any two of us are changed the same way by the same experience.” Yup. Brains are hard.

• The IP metaphor has produced few, if any, insights.

Here, Epstein is dead wrong (i.e., “wildly overstating his case for dramatic effect”). Almost everything we’ve learned about the brain in the last 50 years has come about from the IP metaphor. It’s been incredibly fruitful. But we can do so much better!

• We are organisms, not computers

This, reader, is the magic. This is why the information processing metaphor causes problems. The computer metaphor can help (has helped!) you understand the brain, but if you frame brain function in the computer metaphor, you will miss critical features of the brain’s nature.

The brain is not a Turing machine, capable of any computation. The brain is an evolved structure, honed to produce adaptive action. Higher-level capacities like cognition, intelligence, and memory are built out of sensorimotor capabilities. The very act of perception is inseparable from knowledge of our body’s action capabilities.

• Relevance for writers

The human brain is what it is because of its evolutionary history. All the shiny beautiful new things are built atop of (or, rather, out of) basic functions. If some divine power created the brain from scratch, that scaffolding wouldn’t be necessary. There’s no telling what that brain would look like, but it wouldn’t make the same compromises and tradeoffs you’d find in a brain developed through evolutionary time.

This may not bother most readers, but if divine powers created humans from scratch and stardust three thousand years ago, those non-evolved people would behave nothing like the humans of Earth.